A new strategy for harmonic minimization based on triple switching of multilevel converters

In this paper the Imperialistic competition algorithm (ICA) is used to minimize harmonic components of the output voltage up to 75th harmonic in a multilevel inverter structure with unequal DC sources by the means of selected switching angles. As the number of switching angles increase, it becomes more difficult to calculate the optimum switching angles in order to minimize THD, so the ICA method is used to find the global optimum of the search space. In addition, the topology used in this multilevel converter is an optimum topology with maximum number of output voltage steps while the number of switches is constant.